Si/SiGe near-infrared photodetectors grown using low pressure chemical vapour deposition

Near-infrared photodetectors have been fabricated using standard CMOS processes in conjunction with the multilayer growth of Si/SiGe _0.06 using low-pressure chemical vapor deposition (LPCVD). Cross-section scanning electron microscopy (SEM) indicates the existence of quantum dot like corrugations in devices with particularly thick SiGe _0.06 quantum wells. With an accumulation of germanium atoms at the crest of such features and commensurate high germanium concentration we see a considerable enhancement of the long wavelength detection sensitivity of photodetectors in the range 1100-1300 nm. By fitting experimental data the minimum energy gap of the structure is found to be 0.88 eV corresponding to a germanium concentration of around 15%.